app: drive auto-refresh via gr.Timer().tick instead of every= on Dataframe

gr.Dataframe(every=N) was firing load_leaderboard on the server every
10s (verified via runtime logs), but the component's client-side
re-render after the initial value silently dropped rows added between
ticks. Same shape as gradio-app/gradio#8160 ("when the data already
exists ... it cannot be updated and the page needs to be refreshed").

Switch to gr.Timer(10).tick(fn=load_leaderboard, outputs=df_view).
Identical code path to the manual Refresh button: each tick is an
event fired through the standard component-update channel, which
re-renders reliably. The Refresh button stays as the "I want it now"
override.

app.py

@@ -54,8 +54,13 @@ with gr.Blocks(title="CADGenBench Leaderboard") as app:
             interactive=False,
             wrap=True,
             label="Results (sorted by aggregate CAD score)",
-            every=10,
         )
+        # gr.Dataframe's built-in `every=` doesn't reliably re-render
+        # when rows are added between ticks (gradio-app/gradio#8160).
+        # Drive periodic updates through an explicit gr.Timer event,
+        # same code path as the manual Refresh button.
+        auto_refresh_timer = gr.Timer(10)
+        auto_refresh_timer.tick(fn=load_leaderboard, outputs=df_view)
         refresh_btn = gr.Button("Refresh", size="sm")
         refresh_btn.click(fn=load_leaderboard, outputs=df_view)